Ductile Iron Swing Check Valve for Water, Oil, and Gas Pipelines

Ductile Iron Swing Check Valve Used To Prevent Medium Backflow

This is a swing check valve, a type of check valve. It plays a "one-way passage" role in the fluid pipeline to prevent the medium from flowing back. The following is a detailed analysis from the structure, principle, and application:

Core structure & working logic

Valve body (blue body):

Material: ductile iron (surface anti-corrosion spray), pressure-resistant, corrosion-resistant, suitable for water, oil, light gas and other media. The flanges at both ends connect the pipeline to facilitate splicing with the pipeline network (such as municipal water supply, factory circulating water system).

Casting information: usually marked with nominal diameter (DN) and pressure rating (PN), such as DN100, PN16 (adaptive pipeline size, pressure resistance).

Valve disc (the "door plate" hidden inside):

The core of the check valve: There is a "valve disc" (similar to the structure of a door) that can rotate around the axis in the valve body. When the medium flows forward (along the direction of the pipeline arrow), the thrust pushes the valve disc open (like a door is pushed open), and the pipeline is open; when the medium flows back, the valve disc automatically rotates to close the valve port by its own gravity + reverse medium pressure to prevent backflow.

Flow direction restriction:

During installation, the forward flow direction of the pipeline medium (arrow direction) must be strictly aligned. If it is installed in reverse, the check function will be completely lost, and the valve may even be damaged by backflow impact.

Application scenario & value

Water pump outlet: Same as the previous check valve! For example, the secondary water supply pump of the community and the circulating pump of the factory cooling tower, the valve disc closes quickly when the pump is stopped to prevent water from backflowing and impacting the pump impeller (avoiding the "water hammer effect"-backflowing water may damage the impeller and crack the pipeline).

Large pipeline trunks: urban water pipelines, long-distance oil pipelines, due to the large pipe diameter and strong medium flow inertia, the "large valve disc" of the swing check valve is more suitable - the sealing area is large when closed, the check effect is good, and the valve disc rotates flexibly and is not easy to get stuck (more suitable for large flow scenarios than small-diameter check valves).

Steam system: In some steam pipelines (such as thermal power plants and printing and dyeing plants), when steam condensate flows back, the swing check valve can prevent steam from flowing back and allow condensate to be discharged (but the steam system often uses "drain check valves", which depends on the specific design).

Compared with the characteristics of other check valves

✔️ Suitable for large diameters: The structure of the valve disc rotating to open has small flow resistance (the medium can pass quickly), suitable for large pipelines above DN50 (for example, the valve in your picture is visually DN100-DN200 level).

✔️ Reliable sealing: When the valve disc is closed, the area of ​​contact with the valve seat is large. The greater the reverse pressure, the tighter the seal (but after long-term use, the valve disc may leak due to wear and tear, and regular maintenance is required).

❌ Not suitable for small flow: For small pipes (below DN50), the swing type may cause the valve disc gravity to cause untimely closure. Generally, it is more accurate to choose a "lift check valve".

Simply put, this is the "one-way door god" of large pipelines. It automatically responds to "forward flow and reverse blockage" by rotating the valve disc, protecting the pipeline network from bursting due to backflow and equipment from damage due to water hammer. It is a must-have valve for municipal and industrial large-flow pipelines~

Main Materials

SND Foundry have been specializing in the production and sales of manhole cover and gully grating, valves, pipe & pipe fitings and metal castings products nearly 20 years. It is located in Wu'an Industrial Park, Handan City, Hebei Province. The park is the largest mechanical casting spare parts processing industrial park in Handan, with a complete supporting industry chain and convenient transportation.

SND has fully passed the ISO9001 quality management system certification. During the production process, it implements a number of strict detailed standards and conducts full-process quality control. Our company has well-equipped chemical laboratories and physical performance laboratories. A complete set of testing equipment such as Direct Reading Spectrometer, Metallographic Microscope, Rockwell Hardness Tester, Universal Material Testing Machine, Non destructive testing(NDT), and Three-dimensional Coordinate Measuring instrument can be used to effectively control chemical composition and ensure mechanical performance.

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